Combustion Synthesis of Stoichiometric Cordierite

摘要

The exothermicity and self sustaining chemical reaction involved in the combustion synthesis method, from metal nitrates-urea mixtures, was exploited for the preparation of Stoichiometric cordierite precursor. Magnesium nitrate hexahydrate, aluminium nitrate nonahydrate, and all aqueous silica sol containing 50 wt% solids were combined in the molar proportions correspondent to the Stoichiometric cordierite (2MgO·2Al_2O_3·5SiO_2). The reactants were hand mixed with urea in a wide-mouth vitreous silica basin (300cm~3) and heated up to about 300℃ on a hot plate inside a fume-cupboard, under ventilation. With the rise in temperature, melting occurs and a clear liquid was produced, which boiled and thickened. Then, the reaction vessel was transferred directly to a muffle furnace pre-heated at 500℃, where ignition took place. The foamy powder obtained was calcined at various temperatures from 1050℃ to 1350℃ and characterised by Thermal Analysis, X-ray Diffraction, and Scanning Electron Microscopy.